1. Field of the Invention
This invention relates to a positive type resist composition sensitive to radiations such as ultraviolet ray, far ultraviolet ray including excimer laser and the like, electron beam, ion beam, X ray and the like.
2. Related Art
In claim 4 of Japanese Patent Application KOKAI No. 63-313150, there is mentioned a photosensitive mixture comprising an alkali-soluble novolac resin, an ester of 1,2-naphthoquinone-diazidesulfonic acid and a photosensitizer represented by the following general formula: ##STR3## wherein X' represents a single bond, --CH.sub.2 --, --SO.sub.2 --, --S--, --CO--, --C(CH.sub.3).sub.2 --, --CH--CCl.sub.3 or a group of the following formula: ##STR4##
With the appearance of highly integrated circuits, the design rule for integrated circuits has become finer, and today it is requested to form a pattern of sub-micron order. As its result, a positive type resist is required to have superiorities in sensitivity, resolution, heat resistance, etc. to prior ones using a photosensitive mixture such as that mentioned above. For forming a sub-micron pattern, in addition, it is necessary to enhance not only the resolution of resist but also the adhesion between resist and substrate. Particularly in the formation of contact hole, the shape of hole is improved by carrying out a wet etching before the dry etching perforation of substrate, after formation of resist pattern, and thereby isotropically etching the substrate. If the adhesiveness between resist and substrate is not good, the wet etching is accompanied by a great quantity of side etching which causes a short circuit undesirably.